U.S. patent number 8,215,913 [Application Number 12/103,875] was granted by the patent office on 2012-07-10 for modified darrieus vertical axis turbine.
Invention is credited to Glenn Raymond Lux.
United States Patent |
8,215,913 |
Lux |
July 10, 2012 |
Modified darrieus vertical axis turbine
Abstract
A lift-type turbine comprising at least three blades at
circumferentially spaced positions is supported for rotation about
a vertical axis. Each blade has an airfoil shape to generate a
torque about the axis responsive to wind across the blades. A
support comprising cables under tension is connected between
adjacent ones of the blades to extend generally circumferentially
about the turbine. Accordingly a minimum number of parts form the
structure of the blades while minimizing the drag produced during
rotation thereof due to the support members lying in a common
circumferential path. The tension of the support members can
support the blades in a pre-stressed condition to optimize the
shape and performance thereof.
Inventors: |
Lux; Glenn Raymond (Saskatoon,
CA) |
Family
ID: |
39887191 |
Appl.
No.: |
12/103,875 |
Filed: |
April 16, 2008 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20080267777 A1 |
Oct 30, 2008 |
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Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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60914392 |
Apr 27, 2007 |
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Current U.S.
Class: |
416/195; 416/240;
416/198R; 416/196R |
Current CPC
Class: |
F03D
3/065 (20130101); Y02E 10/74 (20130101); F05B
2240/214 (20130101); F05B 2240/212 (20130101) |
Current International
Class: |
F03D
1/02 (20060101) |
Field of
Search: |
;415/4.2,4.4
;416/195,196A,198R,240,DIG.9 ;290/44,55 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Nguyen; Ninh H
Attorney, Agent or Firm: Dupuis; Ryan E. Satlerthwaite; Kyle
R. Ade & Company Inc.
Parent Case Text
This application claims the benefit under 35 U.S.C. 119(e) of U.S.
provisional application Ser. No. 60/914,392, filed Apr. 27, 2007.
Claims
The invention claimed is:
1. A lift-type turbine comprising: at least three blades supported
for rotation about a vertical axis of rotation of the turbine; the
blades being supported relative to one another at circumferentially
spaced positions about the vertical axis of rotation; each blade
comprising a member having an airfoil shape in cross section such
that the blades generate a torque in a direction of rotation of the
turbine about the vertical axis responsive to a generally
horizontal wind across the blades as the blades are rotated in the
direction of rotation of the turbine; and a support connected
between adjacent ones of the blades to extend generally
circumferentially about the turbine; wherein the blades are
supported substantially wholly by the generally circumferentially
extending support connected between the adjacent blades.
2. The turbine according to claim 1 wherein the support comprises a
plurality of flexible members supported under tension between
adjacent ones of the blades.
3. The turbine according to claim 1 wherein the support comprises a
plurality of flexible members supported between adjacent ones of
the blades such that the flexible members are arranged to curve
outwardly and form a generally circular path when the blades are
rotated about the vertical axis of rotation in operation.
4. The turbine according to claim 1 wherein the support comprises
support members connected between adjacent blades in at least one
common plane lying perpendicularly to the vertical axis of
rotation.
5. The turbine according to claim 1 wherein the blades are arranged
to be supported in a pre-stressed condition by the support prior to
rotation of the turbine.
6. The turbine according to claim 1 wherein the blades are arranged
to be supported in a flexed position by the support prior to
rotation of the turbine.
7. The turbine according to claim 1 wherein each blade comprises a
plurality of blade segments which are connected end to end with one
another and the support comprises a plurality of annular support
members, each annular support member extending circumferentially
about the vertical axis in a respective plane lying perpendicular
to the vertical axis and being connected to the blades adjacent a
junction between adjacent ones of the blade segments.
8. The turbine according to claim 1 wherein there is provided at
least five blades evenly spaced circumferentially about the
axis.
9. The turbine according to claim 1 wherein each blade comprises a
plurality of blade segments including: an upper blade segment
extending radially outwardly at a downward incline from the top end
of the turbine at the vertical axis; a lower blade segment
extending radially outwardly at an upward incline from the bottom
end of the turbine at the vertical axis; and at least one middle
blade segment extending substantially parallel to the vertical axis
between the upper blade segment and the lower blade segment at a
location spaced radially outwardly from the vertical axis.
10. The turbine according to claim 9 wherein each blade segment is
substantially straight in a longitudinal direction of the blade
segment between opposing ends of the blade segment.
11. The turbine according to claim 9 wherein said at least one
middle blade segment extends substantially parallel to the vertical
axis.
12. The turbine according to claim 9 wherein said at least one
middle blade segment spans at least half a height of the respective
blade.
13. The turbine according to claim 1 in combination with an
auxiliary turbine of similar configuration wherein: the auxiliary
turbine is stacked above the other turbine and arranged for
rotation about a common vertical axis with the other turbine; each
blade of the other turbine comprises a plurality of blade segments
including an upper blade segment extending radially outwardly at a
downward incline from the top end of the turbine at the vertical
axis and a lower blade segment extending generally radially
outwardly from the bottom end of the turbine at the vertical axis;
each blade of the auxiliary turbine comprises a plurality of blade
segments including an upper blade segment extending generally
radially outwardly from the top end of the turbine at the vertical
axis and a lower blade segment extending generally radially
outwardly at a downward incline from the bottom end of the turbine
at the vertical axis such that the upper blade segments of the
other turbine and the lower blade segments of the auxiliary blade
segments are substantially parallel; and there is provided an
anchor member anchored at the common axis between the auxiliary
turbine and the other turbine at one end and anchored to the ground
at an opposing end.
14. The turbine according to claim 1 wherein each blade comprises a
plurality of blade segments connected end to end with one another
and wherein at least one blade segment of each blade comprises a
pivotal blade segment which is pivotal about a respective
longitudinal axis relative to the other blade segments of the
blade.
15. The turbine according to claim 14 wherein the blade segments of
each blade comprise an upper blade segment extending radially
outwardly at a downward incline from a top end of the turbine at
the vertical axis and a lower blade segment extending radially
outwardly at an upward incline from a bottom end of the turbine at
the vertical axis, each pivotal blade section being joined between
a respective one of the upper blade segments and a respective one
of the lower blade segments.
16. The turbine according to claim 1 wherein there is provided a
common shaft supported along the axis of rotation and each blade
comprises a continuous arc shaped member supported at opposite ends
at spaced apart positions along the shaft, the support comprising a
plurality of support members spanning under tension between
adjacent ones of the blades in a plurality of generally
circumferential paths about the turbine at spaced positions in a
direction of the vertical axis, the support members being arranged
to support the blades in a flexed and pre-stressed condition.
17. The turbine according to claim 1 wherein each blade comprises a
plurality of blade segments connected end to end with one another,
each blade segment being substantially straight and being joined
with adjacent blade segments by a smooth curved transition.
18. The turbine according to claim 1 wherein there is provided an
upper annular mount and a lower annular mount supported on the
shaft, each annular mount being annular in shape and extending
circumferentially about the vertical axis in a plane oriented
perpendicularly to the vertical axis, the blades being mounted
between the upper annular mount and the lower annular mount at a
top end and a bottom end respectively at circumferentially spaced
apart locations about the vertical axis.
19. The turbine according to claim 1 wherein the support consists
only of a plurality of flexible members supported under tension
between adjacent ones of the blades.
20. A lift-type turbine comprising: at least three blades supported
for rotation about a vertical axis of rotation of the turbine; the
blades being supported relative to one another at circumferentially
spaced positions about the vertical axis of rotation; each blade
comprising a member having an airfoil shape in cross section such
that the blades generate a torque in a direction of rotation of the
turbine about the vertical axis responsive to a generally
horizontal wind across the blades as the blades are rotated in the
direction of rotation of the turbine; and a support connected
between adjacent ones of the blades to extend generally
circumferentially about the turbine: wherein a top end of each one
of the blades is connected with a bottom one of at least one
diametrically opposed one of the blades by an auxiliary support
member spanning under tension therebetween.
Description
FIELD OF THE INVENTION
The present invention relates to a modified darrieus or lift type
turbine in which the blades have a general airfoil like shape and
are supported for rotation about a vertical axis.
BACKGROUND
Modern wind turbines are either horizontal axis turbines or
vertical axis turbines. Horizontal axis wind turbines dominate the
market world wide. They normally have a nacelle, rotor and blades
that sit on top of a tower. The nacelle consists of the generator,
planetary gearing and all the control systems necessary to operate
the turbine. The rotor holds the blades (usually 3) in their
positions while they rotate around the main shaft in the nacelle.
These wind turbines work for many years with little maintenance,
however, they are very expensive. The economics of horizontal axis
wind turbines have been improving, but still need subsidies in most
parts of the world to be an economical energy alternative.
The vertical axis lift type wind turbines (excluding drag type
turbines) such as the darrieus rotor, gyro rotors, or the H style
turbines, have had moderate success. These turbines tend to have
lower overall power efficiency and have little advantage over the
dominant horizontal axis turbines. These turbines, however, do not
need to be turned into the wind, they tend to be quieter and they
have few moving parts.
Most turbines, whether horizontal or vertical axis, typically need
towers to raise the turbines high above the ground surfaces where
the wind velocity is much higher, and therefore, more beneficial.
The towers are an expensive component and in most cases they limit
the size of the turbine.
U.S. Pat. No. 4,134,707 belonging to Ewers and U.S. Pat. No.
6,857,846 belonging to Miller disclose examples of drag type
turbines, rather than lift type turbines. The blades of the drag
type turbines are arranged to rotate the turbines about a vertical
axis by capturing wind energy on the faces of the blades to push
the turbine in its rotation. In a drag type turbine, it is desired
to maximize the overall size of the blades so that the blades span
a maximum area within a given sweep area thereof. Use of various
support arms and cables and the like to support the blades do not
considerably affect the efficiency as the increased drag against
rotation is partially offset by capturing more wind and due to the
limited velocity of the turbine which is effectively limited to the
speed of the wind. Each of the noted documents discloses multiple
turbine sections stacked above one another, however in each
instance a complex framework is required to support the large
blades designed to capture as much wind as possible in a drag type
turbine.
U.S. Pat. No. 7,156,609 belonging to Palley discloses one example
of a vertical axis turbine formed of a plurality of individual
blade sections which are assembled into a complex blade shape. The
blades are supported at top and bottom ends by horizontal portions
which provide drag against rotation without contributing to any
beneficial lift forces to enhance rotation. Drag is typically of
much greater concern in a lift type turbine as such turbines are
most efficient when rotating at speeds which are plural times the
speed of surrounding winds. Furthermore no additional structural
support is provided to the blades along the length thereof which,
in a lift type turbine, can be subjected to considerable
centrifugal forces due to the high rotation speeds as well as
strong lift forces towards the axis of rotation.
U.S. Pat. No. 5,183,386 belonging to Feldman discloses a vertical
axis sail bladed wind turbine in which the blades comprise two
fabric sail portions and a third cable portion arranged to be wound
onto a drum in a collapsed position. The sail portion of the blades
are not suitably arranged to resist strong lifting forces being
generated or strong centrifugal forces from high rotation speeds
and accordingly the turbine has limited application. In general the
vertical portions of the sail blades would have to be quite short
in order to overcome the centrifugal forces acting on them.
U.S. Pat. No. 4,624,624 belonging to Yum comprises a vertical axis
turbine in which the blades are hinged for folding into a collapsed
structure. Only a minimal portion of each blade is positioned at
the outer periphery of the turbine where the turbine is operating
at its greatest efficiency.
SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided a
lift-type turbine comprising:
at least three blades supported for rotation about a vertical axis
of rotation of the turbine;
the blades being supported relative to one another at
circumferentially spaced positions about the vertical axis of
rotation;
each blade comprising a member having an airfoil shape in cross
section such that the blades generate a torque in a direction of
rotation of the turbine about the vertical axis responsive to a
generally horizontal wind across the blades as the blades are
rotated in the direction of rotation of the turbine; and
a support connected between adjacent ones of the blades to extend
generally circumferentially about the turbine.
The support preferably comprises a plurality of support members
supported under tension between adjacent ones of the blades.
Alternatively, the support may comprise an annular member providing
additional support to the blades.
By providing a plurality of blades, for example three or more, and
more preferably five, which are supported by additional support
members spanning under tension between adjacent blades in a
horizontal direction, a minimum number of parts is required to form
the structure of the blades while minimizing the drag produced
during rotation thereof. The support members being connected
horizontally only between adjacent blades when there are three or
more blades results in the support members lying generally in a
common peripheral or circumferential path during rotation so as to
have minimal effect on drag. The tension of the support members can
support the blades in a pre-stressed condition to optimize the
shape and performance thereof. Furthermore, when arranged in a
circumferential path between adjacent ones of the blades and at
various heights along the blades, the support members provide
support against centrifugal forces on the blades during
rotation.
The blades preferably comprise generally elongate and rigid members
and the support members preferably comprise flexible cables
supported under tension.
The support members are preferably between adjacent blades in at
least one common plane lying perpendicularly to the vertical axis
of rotation.
The blades may be supported in a flexed and pre-stressed condition
by the support members.
The support members preferably span generally horizontally between
the adjacent blades.
Each blade preferably comprises a plurality of blades segments
which are connected end to end with one another and wherein the
plurality of support members are connected to the blades at a
junction between adjacent ones of the blade segments.
Preferably there is provided at least five blades evenly spaced
circumferentially about the axis.
The turbine is preferably supported substantially wholly by the
blades and the plurality of support members spanning under tension
between the adjacent blades.
The plurality of blade segments of each blade preferably include:
an upper blade segment radially outwardly at a downward incline
from the top end of the turbine at the vertical axis, and a lower
blade segment extending radially outwardly at an upward incline
from the bottom end of the turbine at the vertical axis.
The blade segments of each blade may also include at least one
middle blade segment extending substantially parallel to the
vertical axis between the upper blade segment and the lower blade
segment at a location spaced radially outwardly from the vertical
axis.
The turbine may be provided in combination with at least one other
turbine of like configuration in which the turbines are supported
stacked above one another for rotation about a common vertical
axis.
In some embodiments, at least one blade segment of each blade
comprises a pivotal blade segment which is pivotal about a
respective longitudinal axis relative to the other blade
segments.
According to a second aspect of the present invention there is
provided a lift-type turbine comprising:
at least three blades supported for rotation about a vertical axis
of rotation of the turbine;
the blades being supported relative to one another at
circumferentially spaced positions about the vertical axis of
rotation;
each blade comprising a plurality of elongate blade segments;
each blade segment of each blade comprising a generally rigid
member having an airfoil shape in cross section such that the
blades generate a torque in a direction of rotation of the turbine
about the vertical axis responsive to a generally horizontal wind
across the blades as the blades are rotated in the direction of
rotation of the turbine; and
at least one of the blade segments of each blade comprising a
pivotal blade segment which is pivotal about a respective
longitudinal axis relative to the other blade segments.
By providing an additional blade segment within each blade which is
pivotal about a longitudinal axis thereof, the performance
characteristics of the turbine can be adjusted according to wind
conditions. For example certain blade segments may be pivoted into
a braking position in which interaction between the blade and the
wind forces applies a braking torque to the turbine about the
vertical axis. As wind conditions vary, it may be subsequently
desired to pivot all blade segments into a position which applies a
torque in a common direction of rotation responsive to wind
forces.
Each pivotal blade section may be joined between a respective one
of the upper blade segments and a respective one of the lower blade
segments.
The longitudinal axis of each pivotal blade segment is preferably
substantially parallel to the vertical axis of the turbine.
According to another aspect of the present invention there is
provided a lift-type turbine comprising:
a plurality of blades supported for rotation about a vertical axis
of rotation of the turbine;
the blades being supported relative to one another at
circumferentially spaced positions about the vertical axis of
rotation;
each blade comprising: an upper blade segment extending radially
outwardly at a downward incline from a top end of the turbine at
the vertical axis; a lower blade segment extending radially
outwardly at an upward incline from a bottom end of the turbine at
the vertical axis; and at least one middle blade segment extending
between the upper blade segment and the lower blade segment at a
location spaced radially outwardly from the vertical axis;
each blade segment of each blade comprising a generally rigid
member having an airfoil shape in cross section such that the
blades generate a torque in a direction of rotation of the turbine
about the vertical axis responsive to a generally horizontal wind
across the blades as the blades are rotated in the direction of
rotation of the turbine.
By forming the blades of a lift type turbine of segments in which
the upper and lower segments form inclined lifting surfaces, a
lower cost and simpler design of blade is produced while taking
advantage of lift forces over the full length of the blade.
Furthermore the portion of the blade at the outer periphery is
increased to maximize the portion of the blade which is rotating at
the periphery at optimum speed for maximizing efficiency.
In some embodiments, each blade segment is substantially straight
in a longitudinal direction of the blade segment between opposing
ends of the blade segment. The middle blade segments may also
extend substantially parallel to the vertical axis at least half a
height of the respective blade.
In some embodiments, the turbines can be stacked one above the
other to take advantage of greater wind speeds spaced above the
ground at higher altitudes without requiring a tower or complex
support structure which does not contribute to producing any useful
power. Stacked turbines in which lift type blades are used, are
anchored through the use of bearings and tensioned cables secured
directly to a shaft at the axis of rotation. The stacked turbines
remain directly adjacent to one another contrary to drag turbine
designs in which the maximized area of the blades interferes with
connecting support cables. Complex support structures are required
in prior art drag configurations of stacked turbines.
When the turbine is provided in combination with an auxiliary
turbine of similar configuration, preferably:
the auxiliary turbine is stacked above the other turbine and
arranged for rotation about a common vertical axis with the other
turbine;
each blade of the other turbine comprises a plurality of blade
segments including an upper blade segment extending radially
outwardly at a downward incline from the top end of the turbine at
the vertical axis and a lower blade segment extending generally
radially outwardly from the bottom end of the turbine at the
vertical axis;
each blade of the auxiliary turbine comprises a plurality of blade
segments including an upper blade segment extending generally
radially outwardly from the top end of the turbine at the vertical
axis and a lower blade segment extending generally radially
outwardly at a downward incline from the bottom end of the turbine
at the vertical axis such that the upper blade segments of the
other turbine and the lower blade segments of the auxiliary blade
segments are substantially parallel; and
there is provided an anchor member anchored at the common axis
between the auxiliary turbine and the other turbine at one end and
anchored to the ground at an opposing end.
In some embodiments a top end of each one of the blades is
connected with a bottom one of at least one diametrically opposed
one of the blades by an auxiliary support member spanning under
tension therebetween.
In some embodiments there may also be provided an upper annular
mount and a lower annular mount supported on the shaft, each
annular mount being annular in shape and extending
circumferentially about the vertical axis in a plane oriented
perpendicularly to the vertical axis, the blades being mounted
between the upper annular mount and the lower annular mount at a
top end and a bottom end respectively at circumferentially spaced
apart locations about the vertical axis.
According to a further aspect of the invention there is provided a
lift-type turbine comprising:
a base annular frame member which is circular about a central
upright axis thereof;
a plurality of blades mounted on the base annular frame member at
circumferentially spaced locations about the base annular frame
member;
a peripheral support system supporting the base annular frame
member thereon for rotation about the central upright axis;
the blades being mounted on the base annular frame member for
rotating movement therewith about the central upright axis;
the blades having an airfoil shape in cross section and being
oriented to effect rotation of the support ring about the central
upright axis responsive to a generally horizontal flow of air
across the blades; and
a generator driven by rotation of the base annular frame member and
blades supported thereon about the central upright axis.
According to yet a further aspect of the present invention there is
provided a lift-type turbine comprising:
a plurality of annular frame members which are supported
concentrically about a central upright axis at axially spaced
positions along the central upright axis relative to one
another;
a plurality of blades spanning across the annular frame members at
circumferentially spaced locations about the central upright
axis;
the blades being mounted on the annular frame members for rotating
movement together therewith about the central upright axis;
the blades having an airfoil shape in cross section and being
oriented to drive rotation of the support ring about the central
upright axis responsive to a generally horizontal flow of air
across the blades; and
a generator driven by rotation of the annular frame members and
blades supported thereon about the central upright axis.
By providing an annular frame member supporting the blades thereon,
the blades have sufficient structural support that no central axle
is necessarily required. Furthermore the annular frame member may
be supported directly on a peripheral support in the form of
rollers at fixed positions about the circumference of the rotor of
the turbine to greatly simplify the support structure required. The
annular frame member also permits a generator to be coupled at a
periphery of the rotor of the turbine to minimize the complexity of
the gearing required. When multiple annular frame members are
provided, the resulting structure of the rotor, including the
blades and the frame members upon which they are supported, is well
supported regardless of whether or not a peripheral support system
or a peripheral generator are provided.
The peripheral support system may comprise a plurality of rollers
rotatably supporting the base annular frame member thereon at
circumferentially spaced locations about the base annular frame
member, the rollers being generally fixed in position relative to
the ground.
The generator may be coupled directly to the base annular frame
member or may be coupled to the annular frame member through the
peripheral support system.
There may be provided a plurality of auxiliary annular frame
members mounted concentrically and axially spaced in relation to
the base annular frame member. Preferably the auxiliary annular
frame members are coupled between the blades to provide auxiliary
support to the blades.
There may be provided a plurality of tension members, each spanning
under tension diametrically across the turbine from an upper end
supported on one of the annular frame members to a lower end
supported on another one of the annular frame members.
There may be provided a brake for restricting rotation of the
blades about the upright axis beyond an upper speed limit in which
the brake is operatively connected to the base annular frame
member.
Some embodiments of the invention will now be described in
conjunction with the accompanying drawings in which:
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A is a side elevational view of a first embodiment of the
turbine.
FIG. 1B is a top plan view of the turbine according to FIG. 1.
FIG. 2 is a side elevational view of the turbine according to FIG.
1 in a stacked configuration.
FIG. 3 is a side elevational view of a further embodiment of the
turbine.
FIG. 4 is a side elevational view of another embodiment of the
turbine.
FIG. 5A is a side elevational view of yet a further embodiment of
the turbine.
FIG. 5B a top plan view of the turbine according to FIG. 5A.
FIG. 6 is a side elevational view of a further embodiment of the
turbine in which the blades are supported in a pre-stressed
condition.
FIG. 7 is a side elevational view of a further embodiment of the
turbine in which the blades have a varying cross sectional
dimension.
FIG. 8A is a side elevational view of a further embodiment of the
turbine including a pivotal blade segment.
FIG. 8B is a top plan view of the turbine according to FIG. 8A.
FIG. 9A is a side elevational view of another embodiment of the
turbine.
FIG. 9B is a top plan view of the turbine according to FIG. 9A.
FIG. 10 is a side elevational view of another embodiment of the
turbine.
FIG. 11 is a top plan view of the turbine according to FIG. 10.
FIG. 12 is a perspective view of another embodiment of the
turbine.
FIG. 13 is a perspective view of a further embodiment of the
turbine.
FIG. 14 is a side elevational view of yet a further embodiment of
the turbine.
FIG. 15 is a top plan view of the turbine according to FIG. 14.
FIG. 16 is a schematic illustration of a portion of an alternative
embodiment.
FIG. 17 is a side elevational view of further embodiment of the
turbine.
In the drawings like characters of reference indicate corresponding
parts in the different figures.
FIG. 18 is a side elevational view of a further embodiment of the
turbine.
DETAILED DESCRIPTION
Referring to the accompanying figures there is illustrated a
vertical axis lift type turbine generally indicated by reference
numeral 10.
Although various embodiments of the turbine are described and
illustrated herein, the common features of the first several
embodiments will first be described herein.
The turbine 10 is supported for rotation about a vertical axis
spanning between a top end 12 and a bottom end 14 of the turbine.
The turbine includes a plurality of blades 16 spanning between the
top and bottom ends of the turbine at evenly circumferentially
spaced positions about the axis of rotation. The blades are all
coupled to one another at the axis at both the top and bottom ends
of the turbine. In the illustrated embodiments, a set of five
blades are provided at an even spacing relative to one another.
Each blade 16 is formed of a plurality of blade segments which are
assembled together at the time of manufacture. More particularly
each blade includes a top segment 18, a bottom segment 20 and at
least one middle segment 22. All of the blade segments comprise a
generally straight member in a longitudinal direction between
opposing ends thereof which is formed of substantially rigid
material having an airfoil shaped cross section such that the
blades generate a torque along the full length thereof between the
top and bottom ends which is in a direction of rotation of the
turbine about the vertical axis responsive to a generally
horizontal wind across the blades as the blades are rotated in the
direction of rotation about the axis thereof.
The top blade segment of each blade is joined with the other blades
at the top end of the turbine at the axis of rotation to extend
downwardly at a radially outward incline to an outer end of the top
segment. Similarly the bottom blade segment 20 joins all of the
other blades at the axis of rotation at the bottom of the turbine
to extend upwardly therefrom at a radially outward incline to a
respective outer end of the bottom segment. The middle segments 22
are arranged to join the top and bottom segments to form a
continuous blade of blade segments connected end to end from the
top to the bottom of the turbine which is formed of like material,
typically having a substantially constant cross section.
A plurality of auxiliary support members 24 are provided in the
form of flexible cables or other suitable members which can be
supported under tension in connection between various points on the
blades to support the structure of the blades of the turbine.
Primary ones of the auxiliary support members span generally
horizontally between each adjacent pair of blades at the junction
between each adjacent pair of blade segments of the blades. When
all of the support members 24 are connected between adjacent blades
in a circumferential direction, each support member 24 forms a
generally annular configuration about the periphery of the turbine
so that as the turbine is rotated the support members remain in a
generally common path to provide minimal drag to the rotating
turbine. A bearing support 26 is provided at the top and bottom
ends of the turbine to rotatably support the turbine. The bearings
support 26 at the bottom of the turbine rotatably supports an axle
28 of the turbine which in turn is coupled to a generator 30 for
generating useable power.
Turning now to the first embodiment as shown in FIGS. 1A and 1B,
the turbine further includes a central column 40 joining the top
ends of the blades to the bottom ends of the blades along the
central vertical axis of rotation of the turbine. The column 40 is
continuous with the axle 28 at the bottom which drives the
generator. In this embodiment, the central column and the
horizontally extending support members 24, comprising cables under
tension, is all that is required to maintain the structural
integrity of the turbine when rotating in use. The column 40 can be
surrounded by a suitable column support or can provide sufficient
structural support to the turbine alone through the bearings 26
that no additional guy wires and the like may be required.
In the first embodiment, there is provided a single middle segment
22 which is straight between the outer end of the top segment and
the outer end of the bottom segment while extending parallel to the
axis of rotation a height which is usually much greater than the
length of either of the top or bottom blade segments so that the
middle segment preferably extends more than half of the total
height of the blades of the turbine. In the illustrated embodiment,
the middle segments are approximately twice the length of either of
the top segment of the bottom segment.
Also in the illustrated embodiment, the substantially straight
segments are joined with one another by respective transition
portions 23 which curved so that the blade segments of any blade
are all smooth and continuous with one another from one segment to
the next.
The blade segments may be all formed identical to one another so
that the blades can be manufactured from interchangeable modular
segments to minimize cost of manufacturing.
Also in the first embodiment, the support members 24 are arranged
in a plurality of generally horizontal lying planes, oriented
perpendicular to the vertical axis, such that each contains a
circumferential path of support members at a different height in
elevation between the top and bottom ends of the turbine relative
to the other planes of support members 24. The different annular
formations of support members are evenly spaced apart between the
top and bottom ends of the turbine.
In the embodiment of FIG. 1A, a plurality of auxiliary support
members 25 are coupled in a radial direction between the central
shaft and the top and bottom blade segments respectively. The
auxiliary support members are arranged in sets, in which all of the
members within a given set are located in a common horizontal plane
perpendicular to the vertical axis and communicate with a
respective one of the blade. The auxiliary support members 25 are
rigid to maintain orientation of the top and bottom blade segments
relative to the shaft.
As shown in broken line in FIG. 1B, the length, tension and weight
of the cable forming the support members 24 is arranged so that the
support members 24 can bow or curve radially outward under
centrifugal force when rotating about the turbine axis during
operation of the turbine. When the length, tension and weight of
the cable forming the support members 24 is optimally selected to
both support the blades, while forming a circular path during
rotation, the support members will typically have a tendency to bow
downwardly slightly between adjacent ones of the blades under force
of gravity when the turbine is static and not rotating. The outward
curving support members 24 during operation cause the support
members to align with one another along a common circular path so
as to minimize drag against rotation and thus optimize efficiency
of the turbine.
Turning now to FIG. 2, the turbine according to FIG. 1 is shown in
a stacked configuration with an additional turbine 10' which is
similar in configuration.
A plurality of anchor members 32 are provided in the form of guy
cables extending from the upper one of the bearing supports 26 to
the ground at a position spaced radially outwardly from the turbine
when the bottom of the turbine is supported on the ground. Due to
the inclined top blade segment 18 of the turbine, the cables
forming the anchor members 32 can be anchored to the bearing
support 26 at the axis of the turbine very close to the top end of
the blades of the turbine by providing a slope on the cable which
is near the slope of the top blade segments or which is shallower
and more horizontal than the top blade segments.
The turbines are stacked one above the other along a common
vertical shaft which defines the common axis of rotation of all the
turbines when yet even further turbines are stacked. Many turbines
may be stacked in series with one another in some embodiments. The
turbines preferably drive a common generator located at the bottom
on the ground with the turbines extending upwardly therefrom. In
this instance bearing supports 26 are provided at the top and
bottom ends of each turbine. Anchor members 32 extend from the
shaft at the axis of rotation from the bearing supports directly to
the ground in a direct path with the turbines remaining closely
positioned adjacent one another due to the sloped top blade
segments which permit the cables to be positioned near the blades
when the slope of the cables defining the anchor members 32 closely
matches the slope of the top blade segments.
The additional turbine 10', shown in FIG. 2 stacked above a first
turbine 10, differs from the first turbine in that the bottom
segment 22 of each blade extends downwardly and outwardly from an
inner end at the vertical axis, to an outer end supporting the
bottom end of the middle segment of the blade thereon. The bottom
segments of the upper turbine 10' and top segments of both turbine
are thus arranged to be substantially parallel to one another and
to the anchor members 32 such that the upper turbine 10' and the
lower turbine 10 can be located very closely to one another for
maximizing the wind force to be captured by the turbines.
The initial cost per square meter of swept area, of a large
turbine, may be considerably higher than the cost per square meter
of swept area of several small turbines. If this is the case it may
be beneficial to build several smaller turbines stacked above each
other. The stacked turbines also take advantage of the stronger
winds above the earth's surface.
Turning now to the embodiment of FIG. 3, a turbine 10 is shown in
which there is provided a pair of middle segments 22 which form an
obtuse angle on the interior side thereof while similarly forming
an obtuse angle with the respective adjacent top and bottom blade
segments so that all of the adjacent blade segments meet at an
obtuse interior angle on any given blade. In addition to the cables
forming the auxiliary support members 24 spanning between the
junctions of adjacent blades, the support members 24 may also be
provided to span from a mid point along each blade segment,
horizontally to a corresponding blade segment at a midpoint there
along of an adjacent blade. The outwardly bent middle section
defined by the two middle segments 22 of the blade provides some
resistance to inward lifting forces directed at the axis of
rotation to resists bending of the blades in use. The embodiment
according to FIG. 3 may also be formed of modular segments during
manufacture, and may also be used in a stacked configuration
similarly to the other embodiments described herein. Guy cables 32
are again used to support the turbine at the top end thereof.
In further arrangements, turbine blades may be formed of segments
similar to the segments of FIG. 3, but the segments are instead
integrally joined with one another by curved intersection portions
of the blades.
In a further embodiment, to also resist forces which act to bend
the blades inwardly towards the axis of rotation, the blades may be
configured to increase the mass thereof at the middle segments 22
or only at a central portion of the blades to increase the
centrifugal forces acting on the blade and offset inward lifting
forces.
Turning now to FIG. 4, a further embodiment is illustrated in which
the turbine generally resembles the configuration of FIG. 1,
however with the addition of auxiliary braces 50 having an airfoil
cross section which span radially from the shaft to a midpoint
along the blades to provide auxiliary support to the blades. In
addition to or instead of, auxiliary supports 52 may also be
provided which are coupled between the central column and the top
and bottom blade segments. A plurality of additional auxiliary
supports 52 may also be added at other locations on the turbine
where support is needed. It is understood that many variations of
supports 52 and cables are possible other than the configurations
of the illustrated embodiment while still falling within the scope
of the present invention.
Turning now to the embodiment of FIG. 5, the turbine 10 is shown
without a central column extending along the length of the turbine
and without guy wires, but rather the turbine structure consists
solely of the blades spanning between the top and bottom ends of
the turbine at the outer periphery thereof so that the blades
comprise rigid self supporting blade segments supported only by
flexible auxiliary support members 24 in the form of cables under
tension between adjacent blades as in the previous embodiment, but
as well as between the top and bottom segments at top and bottom
ends of the turbine in the form of supports 64. Also additional
supports 60 are arranged to span between a location on each top
segment (for example a midpoint) and a similar location (for
example a midpoint) on one or two additional top segments which are
diametrically across the turbine so that when five blades are
provided, the supports 60 form a pentagram configuration. Yet
further supports 64 under tension may be provided which span from
each top segment to at least one diametrically opposed bottom
segment 20 to provide further support to maintain the blades in
their proper orientation. Rigid supports of airfoil cross section
may also be connected horizontally between adjacent blades for
additional support when no central column is provided. Two middle
sections 22 are preferred on each blade in this embodiment with the
blades forming an obtuse interior angle similarly to the embodiment
of FIG. 3. In addition to two middle sections, or in place thereof,
there may also be provided an outwardly curved blade section. The
bottom ends of the blades are suitably braced to a bottom shaft 66
which couples the turbine to the generator to drive the
generator.
The turbines described herein generally comprise lift type turbines
in which the blade speed is at least two times faster than the
speed of the wind. Although the addition of cables to a lift
turbine does provide drag, this drag is minimal when using many
blades because the angle between the cables and the relative wind
direction is less significant with more blades.
The turbines described herein have advantages in that the five
blades provide the turbine rotor with stability as vibrations and
torque ripples are minimal and are easily compensated. Use of
cables under tension provides additional stability as well as
offering very little drag to the system. The resulting construction
is easy to manufacture at a reasonable cost. By stacking the
turbines, advantage can be taken of higher winds above the surface
of the ground.
An advantage of the substantially vertical blades is that all
points along the blades move at the same speed, as opposed to the
curved blades of a darrieus rotor, where each point has a different
velocity and therefore, a different angle of attack. The most
efficient angle of attack is applied along the full length of the
blade instead of just a few points.
Changing the attached angle of the segments can be very important.
The attached angle, or the angle between the chord line and the
radius, can be changed easily with vertical blades. This angle when
adjusted only a few degrees, can improve the turbine efficiency.
Also, a pivot can be provided at the ends of each vertical middle
blade segment to effectively change the attached angle. When this
attached angle is changed significantly, the blade provides more
drag then lift causing the rotational speed to decrease. The
decrease in speed functions as a safety item that protects the
turbine and the surrounds when the turbine would otherwise over
speed.
Sectioned or segmented blades on a turbine could be at various
angles. These angles could change from horizontal to vertical,
however the most efficient turbine would have long vertical or near
vertical blades at the middle sections. On large turbines the lift
force on the blades may be larger than the opposing centrifugal
forces. Providing an outward bend in the middle sections of the
blades can counter these forces. As well, increasing the mass at
this location increases the centrifugal forces. When providing very
long vertical sections, additional support can be provided at
various points along the length thereof, generally in the shape of
airfoils to reduce aerodynamic drag. The additional supports 50 can
be attached between the blades and the center column.
Turning now more particularly to the embodiment of FIG. 6, the
turbine 10 again comprises a plurality of blades 16
circumferentially spaced about a central column 40 for rotating an
axle 28 of a generator 30. As noted above, each blade includes a
top segment 18, a bottom segment 20 and a middle segment 22
connected therebetween. Support members 24 in the form of cables
under tension are connected between adjacent blades 16 in a
horizontal plane lying perpendicular to the vertical axis and at
plural intermediate positions along the height of the turbine. More
particularly the support members 24 are connected to each blade at
an intersection between the middle segment and one of the top or
bottom segments to define two common planes within which the
support members lie in a generally circumferential or peripheral
path about the turbine. By shortening the support members to apply
a tension thereto, the outer ends of the top and bottom segments
can be pulled radially inwardly in a pre-stressed condition which
causes the normally straight middle section to bow outwardly in a
flexed and prestressed condition. The outward bow of the middle
section provides strength to resist inward forces from lift acting
on the blades during rotation.
As shown in FIG. 6 the pre-stressed and outwardly bowed middle
section are shown in solid line as compared to the original
unstressed condition of one of the blades shown in broken line by
reference character 16A which would otherwise appear similar in
construction to the embodiment of FIG. 1 or 4. This configuration
optimizes the shape of the blades while forming the blades of
modular straight sections or segments which can be easily
manufactured and assembled. The pre-stressed condition also applies
some resistance to bending of the blades in use during rotation
thereof to increase the strength and stability of the blade while
minimizing the weight and structural materials required to support
the blades of the turbine.
Turning now to FIG. 7, a further embodiment of the turbine 10 is
illustrated in which blades 16 are again provided with a similar
configuration of a top segment 18, a bottom segment 20 and a middle
segment joined therebetween with additional support being provided
by support members 24 under tension therebetween as described
above. A central column 40 of the turbine rotates with the turbine
to drive an axial 28 of a generator 30 also as described in
previous embodiments. The embodiment of FIG. 7 differs in that the
cross sectional dimension of each blade is configured to be at its
narrowest cross sectional dimension at a vertical center of the
middle segment 22. The cross sectional dimension of the blades
increases towards opposing ends so that the blades are thickest and
have the greatest cross sectional dimension where the top segment
18 joins the top 12 of the turbine and where the bottom segment 20
joins the bottom 14 of the turbine. The varying cross sectional
dimension of the blades also serve to optimize the performance of
the blades and the shape thereof when subjected to bending forces
during rotation of the turbine.
Turning now to the embodiment of FIGS. 8A and 8B, the turbine is
again provided with a similar construction of blades 16 including a
top segment 18, a bottom segment 20 and a middle segment 22 which
are supported by support members 24 in the form of cables under
tension in a circumferentially path about the blades. In this
instance however, each middle blade segment 22 comprises a pivotal
blade segment which is pivotal about a respective longitudinal axis
of the segment which extends in the elongate direction of the
segment to be generally vertical and parallel to the axis of the
rotation of the turbine. Each blade thus includes a middle segment
22 which is pivotal about its respective long axis relative to the
other blade segments between a first position which produces a drag
force to break the rotation of the turbine when rotating in a
horizontal wind, and a second position in which the blade segment
generates a torque about the vertical axis of rotation to urge the
turbine to continue to rotate in the working direction of rotation.
The angular orientation of the middle blade section of each blade
can be adjusted independently of the other blades to optimize
response of the turbine to particular wind conditions while
preventing over speeding of the turbine about its axis of
rotation.
Turning now to the embodiment of FIGS. 9A and 9B, the turbine 10 in
this instance includes blades 16 which are each centrally supported
by a respective spoke member 70 rigidly connected between the
blades 16 and the central shaft 40 of the turbine. The spokes 70
have a cross sectional shape to minimize the drag thereof during
rotation about the vertical axis of rotation of the turbine and are
connected to the respective blades 16 at a vertical center thereof.
Each blade thus extends upwardly and downwardly from the respective
spoke member to opposing free ends 72 thereof spaced above and
below the spoke respectively. The shaft in this instance comprises
a collar rotatably supported about a central column 74 wherein the
axle 28 communicates through the column 74 to the generator 30 so
that rotation of the turbine drives the generator as in previous
embodiments. When a set of three of more blades 16, and preferably
five or more are provided about the vertical axis of the turbine,
the support members 24 can again be provided at plural different
elevations spanning horizontally between adjacent ones of the
blades to form a circumferential or peripheral path about the
turbine as described in previous embodiments. Applying tension to
the support members 24 provides adequate support to the blades 16
to prevent the free ends 72 of the blades from bowing outwardly in
use. By arranging the support members 24 in a circumferential path
connected between adjacent ones of the blades, the cables will
follow one another in a common circular path as the turbine is
rotated without any additional spokes being required which cause
considerably more drag so as to provide adequate structural support
to the turbine while minimizing the drag thereof as described in
the other embodiments of the turbine 10. To further simplify the
construction and amount of material required, the central column 74
may comprise an open truss framework to support the turbine spaced
up above the ground.
As described herein, all of the various embodiments generally
comprise a vertical axis turbine in which a plurality of blades of
generally upright or vertical orientation are provided
circumferentially spaced about the vertical axis of rotation in
which three or more blades, and preferably five or more are
provided at evenly spaced positions about the axis. Each adjacent
pair of the blades are interconnected by a horizontally extending
support member coupled therebetween in which the support members
together from a generally annular path about a circumference of the
turbine so that a common annular support is defined by the support
members 24 or by an annular frame member as defined in the
following embodiments. The configuration of a circumferentially
extending support connected between adjacent ones of the blades
provide support to the blades while the construction thereof
remains in a generally annular path as the turbine rotates to
minimize the drag effect on the turbine which can be considerable
in a lift type turbine which rotates at many times the speed of the
prevailing winds.
Referring now more particularly to FIGS. 10 through 15, further
embodiments of the lift type turbine according to the present
invention are illustrated and generally indicated by reference
numeral 110.
Although there are various embodiments of the turbine 110, the
common features of the next few embodiments will now be
described.
The turbine 110 includes a base annular frame member 112 which is
circular about a central axis 114 about which the base annular
frame member rotates. The base annular frame member 112 supports a
plurality of blades 115 mounted at circumferentially spaced
positions about the periphery thereof. The blades 115 are supported
in a generally upright orientation to extend upwardly from the base
annular frame member 112. Each blade has the general shape of an
airfoil in cross section while being positioned relative to the
annular frame member so as to be oriented to cause rotation of the
annular frame member about the central axis 114 responsive to a
wind blowing across the blades in a generally horizontal
direction.
A plurality of auxiliary annular frame members 117 are also
provided which are mounted concentrically with the base annular
frame member 112 at axially spaced positions spaced thereabove. The
auxiliary annular frame members 117 include an uppermost one which
is connected adjacent the top ends of the blades 115 and one or
more intermediate ones which are connected between all of the
blades 115 at a mid-height thereof spaced substantially evenly
between the base annular frame member 112 and the uppermost one of
the auxiliary annular frame member 117.
The annular frame members 112 and 117 along with the blades 115 are
all coupled together so that the annular frame members support the
blades and join them to form a structurally supported rotor of the
turbine which rotates about the central upright axis 114 about
which the annular frame members are concentrically mounted. The
blades 115 therefore join the annular frame members by spanning
thereacross at the outer periphery thereof.
A peripheral support system is provided in the form of a plurality
of towers 118 which are spaced circumferentially about the base
annular frame member 112. Each tower 118 includes a roller 120 or
wheel supported at a top end thereof upon which the base annular
frame member 112 is rotatably supported. The rollers 120 are
supported at fixed positions relative to the ground about the
periphery of the rotor while being freely rotatable so that the
rotor is rotatable thereon about the upright axis 114.
Complimentary rollers may additionally be provided for engaging the
top and sides of the annular frame members in such a manner so as
to retain the rotor in place engaged on top of the rollers 120 so
that no additional central axle is required.
A plurality of tension members 122 are provided in the form of
cables which span under tension diametrically across the annular
frame members of the rotor. Each tension member is coupled at a top
end to an upper one the annular frame members 117 to span across to
a bottom end coupled on the base annular frame member 112 to
provide additional structural support to the rotor.
A generator 124 is provided which converts rotation of the rotor,
including the annular frame members and the blades supported
thereon, into a different usable form of energy. The generator 124
is coupled directly to the base annular frame member 112 by
connection through one of the rollers 120 of the peripheral support
system to minimize the required gearing required at the generator
input.
A braking system to prevent rotation of the rotor beyond an upper
speed limit is provided in connection with the base annular frame
member or any of the blades supported thereon. The brakes may take
the form of drag elements which increase wind resistance to
rotation of the rotor or may comprise a friction type brake applied
to one of the annular frame members or to one or more rollers
120.
Turning now to the embodiment of FIGS. 10 and 11 in more detail, a
central axle 126 is provided to which the annular frame members are
connected by spokes 128 to provide additional structural support to
the rotor. The spokes 128 could take on the shape of airfoils,
cables, rods and the like and could be connected across the rotor
to connect between diametrically opposed blades or locations on one
or more annular members.
With regard to the embodiments of FIGS. 10 through 12, in a
preferred arrangement the blades are oriented in a vertical
orientation, however as shown in the further embodiment of FIG. 13,
the blades may also be supported at an upward and outward incline
from the base annular frame member to an upper one of the annular
frame members. Furthermore intermediate auxiliary annular frame
members may be provided in greater numbers or may be eliminated
depending on the size and structural support required to a
particular turbine design.
Turning now to the embodiment of FIGS. 14 and 15, the turbine
comprises a Darrieus type turbine in which a central axle 130 is
provided for supporting a plurality of blades 132 at
circumferentially spaced positions thereabout for rotation about an
upright axis of the axle 130. This configuration is similar to many
conventional type Darrieus rotors. The turbine of the embodiment of
FIG. 14 is distinguished in that annular frame members 134 are
provided which are mounted concentrically about the axle 130 at
axially spaced positions with a radius matching that of the blades
132 at the elevation where the annular frame members are mounted.
Each annular frame member thus joins all of the blades which are
accordingly mounted about the circumference thereof. The blades 132
accordingly span across the annular frame members which provide
additional structural support to the blades for increasing the
reliability and minimizing maintenance associated with the turbine.
Additional support members 136 in the form of cables may also be
provided similarly to the previous embodiments to span horizontally
under tension between adjacent ones of the blades.
Turning now to FIG. 16 a variant of the embodiments of FIGS. 10
through 13 noted above is shown in which the base annular frame 112
is instead fixed relative to the ground on suitable supports with
the rollers 120 being supported at the bottom ends of the blades
115 for rotation with the turbine about the vertical axis.
Accordingly, the rollers 120 roll along the fixed frame 122 which
functions as a track. Additional annular frame members 117 may be
provided in a circumferential pattern about the blades as required
for strength. In further arrangements the rollers maybe supported
on an annular frame member that rotates with the blades while
remaining rolling along the base member 112 which defines the
annular track upon which the turbine is rotatably supported
according to the embodiment of FIG. 16. In this instance the
generator is driven through an auxiliary roller rolling along one
of the annular frame members of the turbine or through a central
shaft coupled to the turbine for rotation therewith.
Turning now to FIG. 17, a variant of the turbine according to FIG.
6 is illustrated in which the blades are instead formed of
continuous generally semi-circular arcs or are formed in full
circles to define two diametrically opposed blades when mounted on
the shaft 40. The blades 16 of the embodiment of FIG. 17 thus each
comprise a continuously formed arc of common and integrally formed
material spanning between opposing ends of the blade which are
anchored in fixed relation onto the shaft 40 at axially spaced
positions at respective top and bottom ends thereof.
In FIG. 17 the original shape of the blades are shown in broken
line prior to being flexed and shaped into a prestressed condition
by the flexible support members 24 spanning under tension between
adjacent ones of the blades in a generally circumferential path as
in previous embodiments and by auxiliary supports 50 in the form of
rigid struts spanning either between the central shaft 40 and
respective ones of the blades in a radial direction or spanning
between adjacent ones of the blades in a generally circumferential
pattern similarly to the support members 24.
In a preferred arrangement one set of rigid supports 50 maybe
provided at a prescribed spacing in the axial direction from each
end of the turbine so as to define the upper segments 18 of the
blades as the portion extending above the first set of supports 50,
to define the middle segments 22 of the blades as spanning between
the two different sets of support members and to define the lower
segments 20 of the blades as extending between the lowermost set of
the supports and the bottom end of the shaft. Each of the upper and
lower segments of the blade 18 and 20 respectively extend radially
outwardly from the shaft of the turbine at respective downward and
upward inclines similarly to the previous embodiments.
The flexible support members 24 are arranged under tension at
various intermediate locations to shape the blades so that the
middle segments of the blades are generally flatter than upper and
lower curved segments formed above and below each middle segment.
The curved segments above and below each middle segment form
transitions at the location of the supports 50 where there is a
greater curve in the blade as the blade transitions into the
straighter upper and lower segments defined relative to the
supports 50.
In further embodiments any combination of supports 50 which are
rigid and support members 24 comprising flexible cables under
tension maybe used to shape continuously formed blades into any
desired shape relative to the shaft 40 to which the blades are
anchored at opposing ends. In preferred arrangements the blades are
flexed and shaped into a prestressed condition such that a defined
middle segment thereof is generally straighter and near vertical or
parallel to the vertical axis as compared to remaining portions of
the blade above and below the defined middle segments.
As described and illustrated herein, the proposed turbine design is
a vertical axis turbine. The blades, which have a cross sectional
shape similar to airfoils, are mounted vertically in some
embodiments. They are attached to one or more generally annular or
circular rings of cables or support members 24 under tension, or
annular frame members, and may or may not rotate around a tower.
The annular rings and blades may be attached to the pivot point of
a central axle with arms or spokes. As shown in some embodiments,
the annular frame members may be supported by rollers between the
lowest ring and the surface. These rollers may be attached to the
ground, the rings or to the blades. The support rollers may also
follow a designated path similar to rail cars following a track on
a railroad system, or cars on a roller coaster. If the rollers
follow a track, a tower and arms may not be necessary.
The support members 24, as described above in the first few
embodiments, can be applied to all of the designs of turbines 10
and 110 noted herein with the same benefits being realized of
providing lightweight structural support with minimal drag when
provided in a circumferential path due to the tracking of the
cables with one another during rotation of the turbine.
According to the later embodiments, the modular turbine consists of
sectional rings and blades. Each section of ring and each section
of blade can be assembled at ground level and inserted below the
lowest ring. Most blade and ring sections would be similar and
therefore manufacturing costs would be decreased.
The diameter of the turbine is completely variable. However, a
larger diameter will have less centrifugal force on the rings and
blades. The blade speed is usually constant, and therefore
independent of the diameter. The number of blades, the length of
the blades, and the number of rings is also variable, but would be
restricted by the stability of the rotor.
A large diameter rotor (rings) would support more rings or longer
blades and, therefore, would take advantage of the higher wind
speeds above the earth's surface. As the number of rings increase
or the blade length increases, cables could be attached wherever
necessary to help strengthen the rotor. These supports could be
attached between blades, blades and rings, rings and rings, blades
and tower, rings and tower or any combination needed for rotor
strength and support. Also, more rollers or bigger rollers could be
added for more support for the heavier structure.
Rollers can be attached to the surface for support. A generator
could be connected to one or more spinning rollers for the
extraction of electrical energy. The generator could also be
mechanically connected to the rotor with a separate system. This
system could use wheels, rollers, gears, pulleys, chains, belts or
any combination to form a mechanical drive train that would convert
the rotational speed of the turbine into electrical energy. This
connection, if attached at the outer circumference would not likely
require an increase in generator speed and therefore, a planetary
or gear increaser would not be necessary.
The rollers or wheels could also have brakes attached to them and
could be used to stop the turbine when necessary. Wind turbines
must never over-speed. If over-speeding occurs, the generator may
be overheated and burn out, or the turbine itself may destruct.
Over-speeding may be prevented by adding drag devices or air brakes
such as flaps or airfoils to the blades or rings. These devices
would only provide excessive aerodynamic drag when the turbine is
overspeeding. These devices could be controlled by centrifugal
forces or by a microprocessor.
The turbine according to the present invention can be manufactured
and assembled for a fraction of the cost of existing turbines.
Also, there are fewer size restrictions on a turbine as described
herein. Presently, horizontal axis and vertical axis wind turbines
are restricted in size due to strength of materials and economics.
The present turbine designs could have a diameter measured in
1000's of meters with heights exceeding present day turbine
heights. Massive steel towers may not be required. Furthermore,
higher power efficiencies can be obtained due to larger diameters
and larger blades (resulting in higher Reynolds Number). In the
turbines described herein, the only moving parts are close to the
ground (with the exception of the air brakes which are only used in
emergency situations for ease of maintenance. Other advantages
include the elimination of gear increases and the ease of assembly
of the turbine.
In further embodiments, the number of rings or annular frame
members can be varied. The number of rollers can also be 1 or more.
The turbine may not need a central pivot point or central tower
support if a track (similar to a railway track) is being used. The
number of blades and the size of each blade are completely
variable. The number of blades between each ring may also vary.
Rollers may be needed under, above or on the sides of the rings to
keep the rotor in place. The rollers can be attached to the
surface, the rings or the blades. The blades do not have to be
vertical. The path outlined by a complete revolution may have a
larger or smaller diameter as the blade extends above the surface.
The rings may have various diameters.
In general, in the embodiments of FIGS. 10 through 13, circular
rings are used to join the blades together to make a solid rotor in
a vertical axis lift type turbine. Rollers between the bottom ring
and the surface are used to stabilize the rotor. The rollers or the
rings can be used to extract power. The rollers, which already have
a high angular velocity, can be connected to the generator by use
of a drive shaft. The rings, which have a high tangential velocity,
can be connected to a generator by use of rollers, gears, pulleys,
chains, belts, etc.
In further embodiments, any number of tension members or spokes may
be provided as required for structural integrity of the various
illustrated embodiments by spanning between blades, annular
members, a central axle or any combination thereof. The embodiment
of FIG. 12 for example may include a plurality of spokes or tension
members spanning diametrically across the rotor between opposed
blades or opposed portions of one or more annular frame members.
Location of the annular frame members may also be varied so that
the blades extend either above or below a respective uppermost or
lowermost one of the annular frame members.
Turning now to FIG. 18 a further embodiment of the turbine 10 is
illustrated in which a set of five blades 16 are mounted
circumferentially about the vertical axis of rotation of the
turbine similar to previous embodiments. In the embodiment of FIG.
18, there is provided an upper annular member 200 and a lower
annular member 202 between which the blades 16 are mounted. Each of
the upper and lower annular members is generally annular in shape
so as to extend circumferentially about the vertical axis of
rotation concentrically therewith in respective horizontal planes
oriented perpendicularly to the vertical axis. Each blade 16 is
mounted at a top end on the upper annular member 200 and at a
bottom end on the lower annular member 202 so as to extend between
the upper and lower annular members at circumferentially spaced
positions thereabout. Each of the upper and lower annular members
can be joined to a central shaft 40 by suitable spoke members 204
which extend generally radially between the shaft 40 and the
annular member similar to the auxiliary support members 25 shown in
FIG. 1A.
The blades 16 in the embodiment of FIG. 18 comprise only a
plurality of intermediate segments 22 which are joined end to end
with one another so as to form a continuous and outwardly curved
blade 16 which is spaced outwardly at the vertical center thereof
relative to the periphery of the upper and lower annular members.
In FIG. 18, eight segments 22 are shown on each blade however more
or less segments may be provided as desired. A greater number of
segments better approximates a Darrieus type rotor however a fewer
number of segments is easier to construct. Each of the segments is
typically a rigid section of the blade which extends substantially
straight between the opposed ends thereof. The adjacent sections
are joined at an obtuse interior angle relative to one another to
form the gradually outwardly curved profile of the overall
blade.
Similarly to the previous embodiments, a plurality of
circumferentially extending supports 24 are provided in respective
horizontal planes to be connected between adjacent ones of the
blades in a generally circular pattern about the periphery of the
turbine. Each circumferential support 24 is located at a respective
horizontal plane oriented perpendicularly to the vertical axis of
rotation. A circumferential support 24 is provided at a junction
between each adjacent pair of blade segments of the blades 16 of
the turbine. The circumferential supports 24 typically comprise
flexible cables spanning under tension between adjacent ones of the
blades to provide adequate support to the blades.
In addition to the circumferential supports 24, a plurality of
transverse supports 64 may also be provided in the form of cables
extending under tension similar to the embodiment of FIG. 5A. In
the embodiment of FIG. 18, a top end of each blade 16 is connected
to the bottom end of two other blades which are generally
diametrically opposed therewith relative to the vertical axis of
rotation by one of the transverse supports 64. When providing a
plurality of transverse supports 64 interconnected between opposed
ones of the blades at opposed top and bottom ends thereof, a
central shaft may not be required which extends between the top and
bottom ends of the turbine and accordingly only a small shaft 40 is
provided between the spokes 204 of the lower annular member and the
generator 30. In addition to no central shaft being provided
between the top and bottom ends of the turbine, no additional
anchors or guy wires are required to be connected between the top
end of the turbine and the ground due to the structural support
provided by the transverse supports and the upper and lower mounts.
Similar to previous embodiments, the generator 30 is driven to
rotate by rotation of the turbine and the shaft 40 rotating with
the turbine which connects to the generator.
The spokes and tension members in the various embodiments of the
present invention may comprise rods, flat shapes or airfoil shaped
tension devices if the circular shape of a cable provides too much
aerodynamic drag to be practical.
In yet further embodiments, the rollers may be attached to the
blades for movement about the central axis therewith. In this
arrangement, the generator could be built inside the blades and
mechanically connected to the rollers.
Since various modifications can be made in my invention as herein
above described, and many apparently widely different embodiments
of same made within the spirit and scope of the claims without
department from such spirit and scope, it is intended that all
matter contained in the accompanying specification shall be
interpreted as illustrative only and not in a limiting sense.
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